1. Field of the Invention
The present invention relates to color proofing films. More particularly, the invention relates to a novel spot gloss layer for color proofing film systems. Such films permit the selective application of a gloss to a color proofing film image.
2. Description of the Prior Art
In the field of lithographic printing, it is desirable to produce a multicolor proof to assist in correcting a set of color separation films prior to using them to produce metal based lithographic printing plates. The proof should reproduce the color quality that will ultimately be obtained during the printing process. The proof must be a consistent duplicate of the desired halftone image. Visual examination of a color proof should show the color rendition to be expected from a press printing using the color separations, and any defects on the separations which might need to be altered before making the printing plates. There are two general types of photoimaging methods, namely the overlay type and the single sheet type.
In the overlay type of color proofing method, an independent transparent plastic support is used for producing an image of each color separation film by applying a photosensitive solution of the corresponding color. The supports carrying images of the corresponding colors are then superimposed upon each other over a white sheet to produce a color proofing composite. Examples of such overlay approaches are contained in U.S. Pat. Nos. 3,136,637; 3,211,553; and 3,326,682.
In the single sheet type of color proofing, a color proofing sheet is prepared by successively producing images of different colors from different color separation films on a single receiver sheet. This can be accomplished by sequentially applying colorants or colored, photosensitive layers to a single opaque support. Examples of such single sheet approaches are contained in U.S. Pat. Nos. 3,574,049; 3,671,236; 4,260,673; 4,366,223; 4,650,738; 4,656,114; and 4,659,642. Various processes for producing single sheet color proofs of an image embodying thermal transfer and photopolymerization techniques are known, for example, from U.S. Pat. Nos. 3,060,023; 3,060,024; 3,060,025; 3,481,736; and 3,607,264. Peel apart color proofing systems are also well known. U.S. Pat. Nos. 4,963,462; 5,049,476; 4,910,120 and 5,108,868, which are incorporated herein by reference, disclose peel developable, single sheet color proofing systems. U.S. Pat. No. 4,489,154, discloses a process which produces a single layer color proof by peel development. U.S. Pat. No. 5,300,399, which is incorporated herein by reference, discloses a peel apart color proofing system to produce a negative-acting color proofing film.
In the production of such color proofing films, it would be desirable to apply a glossy finish to selected portions of the image. It would be further desirable to apply a matte finish to an image and to achieve a double effect where certain areas of the receiver sheet are made glossy, while other areas are either not made glossy or are actually made partially or completely matte. It has now been unexpectedly found that by applying a gloss layer to an image bearing substrate using the peel-apart photographic element of the present invention, a gloss layer is applied to selected areas of the image, that is, a gloss remains where the gloss layer has been exposed to actinic radiation and transferred onto the image, while the image portions corresponding to the unexposed, removed areas of the gloss layer remain non-glossy or are made partially or completely matte. The gloss layer of the present invention comprises a translucent, photosensitive composition having imbedded particulate matter therein. When imagewise transferred to the surface of the image, a glossy sheen is applied to desired portions of the image. Optionally, the imbedded particles can cause the non-image areas of the gloss layer to emboss the balance of the image, resulting in a matte surface to the balance of the image.